In conjunction with a progress of a refining of a semiconductor device, it is demanded to form a fine pattern which is equal to or less than a resolution limit of a lithography. As a method of achieving this, there has been known a so-called side wall transfer process of leaving a spacer film by forming the spacer film in both side walls extending in a longitudinal direction of a fin shaped core film formed by a lithography and thereafter removing the core film. In this case, the spacer film is formed as a loop shape which connects between both the side walls of the core film at a terminal end in the longitudinal direction of the core film, and the spacer films formed on both the side walls of the core film are shorted therebetween. Accordingly, it has been cut the loop portion of the spacer film.